Did you upload these files from the PLC? If so the documentation is not stored in the PLC, you need the PC that the program was created/stored on or a floppy disk, etc. containing the original program.
This is a very short piece of code, so if you do not have the original copy, you will have to create your own documentation. If you know the machine it should not be too difficult. If any one is to be able to help you any further, they will need more information. What are the inputs? pushbuttons, sensors, limit switch, etc.? What are the outputs? and what are they doing?
Good Luck